14 - Useful Tips

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Transfer a digitized contour map onto 2D and 3D Seismic Sections

Transfer an contour map interpretation onto Seismic Section

Have you every wanted to transfer a map interpretation onto seismic lines? Here is how to import a contour map into SeisX, grid these data and transfer the grid values to all your 2D and 3D seismic lines in a single step.

Note the reef to the left. The green horizon was extracted from a hand contoured map that was digitized and input into SeisX. A possible interpretation is the pale blue event that closely follows the old map. I have interpreted a possible Nisku buildup directly under Well-F and the high reef edge around shot point 450. What characteristics have I used?

Here is the "map" area with several north south trending reefs. The black contours were digitized from an old hand contoured map. All of the Seismic lines, including the 3D survey to the northeast had horizons created by sampling the original map. All you have to do is check the interpretation and determine those areas where additional potential may exist. To be able to do this you need to have is a digital representation of the contours or a series of X, Y, and Z data points for input into SeisX.

First step -- Prep the data

The contour surface can be imported directly into SeisX in Photon Ascii format using the and the icons. The data should be in Photon Ascii format. Refer to the section on awk to get some tips on how to reformat data into SeisX Photon Ascii.

These data could also be gridded directly using Horizon, grid and contour, .

Grid the digitized contour lines

Select (Horizon), (Grid and Contour), ASCII data and the file named above. In this case it is called Dnvg_D3. You might want to specify a polygon (gridpoly) to control the exact size of the gridded area. I have found the gridding and contouring to be very fast in SeisX. You can use a smaller grid increment if you like. The search radius is specified as a Maximum Gridding Distance, it defaults to 3.5 grid cells. You might want to change this value.

Transfer the Grid to Horizon

In order to transfer your grid onto all seismic lines, select (Horizon) (Transfer Grid to Horizon). Select your input grid, use the default radius of 100 meters and select the 2D and 3D lines you want transferred. You might want to user a Polygon Inclusion. Simple! Be sure to toggle on the Overwrite Picks if you transfer the picks a second time.

Now it is easy to update and refine all the seismic lines for the Top Reef. Spend some time to interpret these data. Where do you think there might be some additional potential?

Unix Tricks -- Helpful hints

Set up some symbolic links to point to the SeisX data server. This will reduce the need to click the mouse through the Unix file system. I like starting these links with the letter "a" so they sort to the top of the list.

cd /data/projects/index
ln -s /data2/seisx a-seisx

Here is the "best" way to copy data under Unix to preserve links etc. the following will copy directory inner and place it under the path specified after the cd command. I use this technique to move data around a Unix network all the time. If is a slick application of tar!

tar -cf - inner  | (cd /data/sparky/user/seisx; tar -xBpf - )

Reformatting awks

One of my favorites is a little programming language called "awk", invented by Aho, Weinberger, and Kernighan. I won't go into the syntax of the language since it can be easily be figured out from the man page (or better still, buy the book "The AWK Programming Language". The awk language will run under the korn shell as implemented by SeisX on the NT platform. I will share a few scripts which I wrote to help me get more productive (or unproductive as I am always tweaking them a little bit) awks you may find useful:

Well Data Input

• awk -f dev2sx.ak < deviated.csv > deviated.pha

  The dev2sx.ak takes a comma separated depth, azimuth, inclination file and builds an asc file for input into SeisX

•  awk -f wlsa2sx.ak < wells.csv > wells.pha 

  The wlsa2sx awk will take a comma delimited EXCEL well data base and reformat to SeisX .pha. The order of the data in the Spreadsheet is in the SeisX order. The Tops long name must be on the first line and the short name on the second. This awk will also work to take data from an Access database with a query to produce the SeisX order.

Seismic SEGY

•  awk  -f rename.ak < junk > junk.job

  The rename awk takes long complicated seisX external line and takes the prefix(upt to the first ".") and outputs a constant name. The file junk was built with the Unix command

   ls > junk 

•  awk  -f batchit.ak < junk > junk.job

  The batchit awk generates a SeisX batch file for execution taking the seismic lines names from the file called junk. The present flow: Filter 15-20-55-70, Resample 4ms, 500agc, 5000rms. The batch execution is started with the

   spt_process batchit.job

  command. I use this awk all the time to condition my data before I run a misstie.

•  awk  -f convert.ak < junk > junk.job 

  The convert awk generates a batch file for execution to physically apply the time shift file to the seismic lines. It takes as input a list of lines, applies static shift from the "statshift" in the project directory and writes out a new data set using the name up to the first dot Use this job to permanently apply static shifts if you are loading data into a Landmark project.

•  awk -f pha2segp.ak < navigation.pha > navigation.segp 

  The pha2segp awk takes as input a photon asc file of XY's and reformats the data into SEGP. This file can be used to update other map projects.

Culture, Contours, Lineaments

•  awk -f ex2cnt.ak < horizon > horizon.cnt 

  The ex2cnt awk reads a file of xyz's and reformats into a contour file. Individual contour lines must have the same z value. Contour lines will be separated as the Segid field changes.

•  awk -f ex2xyz.ak < horizon > horizon.xyz 

  The ex2xyz awk reads an excalibur x y z file to a create a SeisX .xyz file that can be read, gridded and contoured in one step

Batch Processing

SeisX does not have the ability to "save" processing flows. Here is a simple way using awk to generate a standard flow:

• Create a file called junk for the SeisX files you want to process with the Unix command

   ls *sgy > junk
   more junk
   101.STK.0.sgy
   102.MIG.0.sgy
   103.MIG.0.sgy
   104.MIG.0.sgy
   105.MIG.0.sgy
   106.MIG.0.sgy
   107.MIG.0.sgy
   

• Edit the batchit awk to adjust the filter, resample interval, AGC and final RMS scale factor.

• Run the awk script:

   awk -f batchit.ak < junk > junk.job
   

• Check your card deck to verify correct data path for reading and writing your seismic data. Here is what mine looks like for the first seismic line:

   # spt_process batchit.job
   $INPUT
   SYSTEM_PATH C:/Paradigm/SeisX34/seisx_support
   FILE 101.STK.0.sgy
   FMT_FILE C:/Paradigm/SeisX34/seisx_support/segy_v3.fmt
   #END_PARMS
   $FILTER
   1.500000e+01 2.000000e+01 5.500000e+01 7.000000e+01
   #END_PARMS
   $RESAMPLE
   4.000000e+00
   #END_PARMS
   $AGC
   5.000000e+02 5.000000e+03
   #END_PARMS
   $OUTPUT
   FILE Seismic/101.STK.3.sgy
   FMT_FILE
   DESC 4ms,15-20-55-70,500agc,5000rms
   FORMAT 16_BIT_INT
   #END_PARMS
   #PROCESS
   $INPUT
   

• Now submit this job that will filter, resample, scale, change it's name to fit into the SeisX world and deposit the final file under the Seismic directory.

   spt_process junk.job
   

  It is left as a homework assignment to edit the batchit.ak awk for your own customized processing flow and where your want to read and write the data! Here is what the processing messages should look like:

   Processing File 101.STK.0.sgy Trace   610 of  2263
   Processing File 101.STK.0.sgy Trace   620 of  2263
   Processing File 101.STK.0.sgy Trace   630 of  2263
   Processing File 101.STK.0.sgy Trace   640 of  2263
   Processing File 101.STK.0.sgy Trace   650 of  2263
   Processing File 101.STK.0.sgy Trace   660 of  2263
   Processing File 101.STK.0.sgy Trace   670 of  2263
   Processing File 101.STK.0.sgy Trace   680 of  2263
   Processing File 101.STK.0.sgy Trace   690 of  2263
   Processing File 101.STK.0.sgy Trace   700 of  2263
   Processing File 101.STK.0.sgy Trace   710 of  2263
   Processing File 101.STK.0.sgy Trace   720 of  2263
   Processing File 101.STK.0.sgy Trace   730 of  2263
   Processing File 101.STK.0.sgy Trace   740 of  2263
   Processing File 101.STK.0.sgy Trace   750 of  2263
   Processing File 101.STK.0.sgy Trace   760 of  2263
   Processing File 101.STK.0.sgy Trace   770 of  2263
   Processing File 101.STK.0.sgy Trace   780 of  2263
   Processing File 101.STK.0.sgy Trace   790 of  2263
   Processing File 101.STK.0.sgy Trace   800 of  2263
   Processing File 101.STK.0.sgy Trace   810 of  2263
   ...
   

  The user needs to select Project, attach SeisX files and the interpreter is ready to start.

Apply Static shifts from Grid Balance without Processing all lines

How do I compute and apply static shift without processing all seismic lines?

Answer: Calculate the solution but do not submit the job. After a successful calculate (no beeps or unconnected seismic lines), use the Unix move command

 mv statshift.MIG.2 statshift.MIG.1 

to take these shifts and apply them to the input data. In order to Select a Reference, turn the Use Line Groups to No. You are then able to select your Reference Line.

Formulas are automatically stored for Horizon Computations

In Horizon Computations, formula expressions are automatically stored for each output Horizon. Just press the Load formula expression button on the Horizon Computations menu.

SeisX will automatically remember the formula based on the Output

Interactive Well Log Tops Picking

SeisX Versuion 3.4 can be used to rapidly pick well log tops

Here I added the tops horizon DNVG the hot lime marker around the Dunvegan. This is the high amplitude event that isochrons are made from. The icon with the letter "T" is used to update the database when the slider bar is placed at the correct event. It is suggest that the user make use of the Criteria expression

ncurves and include ("poly")

to simplify the copying of a specific top depth to a group of wells. Specify the top depth as an elevation, say -500 to you can easily tell what has yet to be edited. Save to all your criteria Wells (wells with log curves and inside your polygon) Then use the button on the well log display to drag the top to the correct position. You might want to copy a specific top depth to a group of criteria wells.

Copy logs.default alias file

If your company has it's own set of log curve names, be sure to copy

logs.default

into your new SeisX project directory. Check the permissions on this file. You may have to change it from read only to all permissions.

What's Different with NT SeisX

• Permissions -- the NT operating system will automatically update permissions to Read only on a random basis (for me, about once a month). If you can't update a SeisX file, check the permission status. With the NT explorer, select Properties, Security and Permissions. If they are set to read only, have your Administrator open up the permissions on all files.
• Color Flash problem -- To reset all your windows double click on the SeisX 3D/2D Seismic Interpretation window to fill the complete screen, double click a second time to re set the window to it's original size. All windows should have the correct color.
• File names are NOT case sensitive. File and file will be treated the same by NT.
• The Korn Shell can be used to access some Unix tools, the editor vi, awk, grep etc. Executables in the Korn shell must be prefixed with "./"
• Change directory with the command "cd d:"
• Do not backup your data when you are running SeisX. NT will not back up any files that have been "touched" by another program!
• Use

  tar -xvf /dev/rmt0 

  to read a tar tape or

   tar -xvf /dev/nrmt0 

  to read multiple tar files on a tape
• Use

  dd if=/dev/nrmt0 bs=30000 of=101
  dd if=/dev/nrmt0 bs=30000 of=102
  dd if=/dev/nrmt0 bs=30000 of=103
  

  Note the no rewind option

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Copyright © Eric Keyser --Last Modified: July 15, 1999